Textile product and process for making same

ABSTRACT

AN ANTISTIC AND FLAME RETARDANTTEXTILE PRODUCT HAVING A BASE AND A PILE SURFACE OF YARN WHICH IS SUSCEPTIBLE TO THE GENERATION AND/OR ACCUMULATION OF STATIC CHARGE AND/OR HAVING THE QUALITY OF ALLOWING FLAME SPREAD, AN ADHESIVE ON THE OPPOSITE SURFACE OF THE TEXTILE PRODUCT AND AN ELECTRICALLY AND THERMALLY CONDUCTING, STATICDISSIPATING METAL FOIL BONDED TO THE OPPOSITE SURFACE OF THE PRODUCT BY MEANS OF THE ADHESIVE.   D R A W I N G

April 1 7, 1973 w. H. COCHRAN u 3,

I TEXTILE PRODUCT AND PROCESS FOR MAKING SAME Filed March 17, 1970 1 v MN WW6 w w. m xwz4f 2% vigil/fi ???5/1/149 w United States Patent3,728,204 TEXTILE PRODUCT AND PROCESS FOR MAKING SAME William H. CochranII, P.0. Box 32, Stonington, Conn. 06378 Continuation-impart ofapplication Ser. No. 765,267,

Oct. 4, 1968. This application Mar. 17, 1970,

Ser. No. 20,200

Int. Cl. D03d 27/100; D04h 11/00 US. Cl. 16166 Claims ABSTRACT OF THEDISCLOSURE The present application is a continuation-in-part of Ser. No.765,267, filed Oct. 4, 1968 and now abandoned, the subject matter ofwhich is incorporated herein by reference.

In said application Ser. No. 765,267, I have described and claimed atextile product, e.g. a tufted or woven carpet, which is provided withunique means for dissipat ing static charges. This is accomplished,according to the invention desrribed in Ser. No. 765,267, by bondingaluminum foil or other electrically conducting metal foil, to the bottomof the textile in direct electrically conducting contact with thesurface yarns, the bonding means comprising an open, unitary network orWeb of overlapping and/or intersecting, hot-meltable thermoplastic,preferably polyester, fibers or filaments. The hotmelted fibers orfilaments of the web penetrate into yarns with which they are in contactto give an extremely strong bond between the aluminum foil and thetextile but without otherwise significantly changing the interfacialrelationship between the foil and the textile. In other words, thebonding Web on hot melting simply penetrates into the fabric which isadjacent to it, i.e., it does not fiow together to form a continuousfilm, the openings or voids initially therein remaining as is. Thisgives the desired bonding eifect, the melted filaments of the webpenetrating well into the fabric, while at the same time, the foil andfabric are maintained in electrically conductive relationship in thoseareas opposite the openings or voids in the Web. In this way, staticdeveloping on the surface yarn of the carpet or like product isdischarged through the foil notwithstanding the adhesive bonding betweenthe foil and textile.

As indicated in Ser. No. 765,267, the failure to provide for botheffective bonding and electrical contact between the textile andconductive'foil has been one of the reasons why aluminum foil had notpreviously been successfully used to dissipate static charge. Otherdifficulties encountered in prior efforts to use foil are also listed inSer. No. 765,267, e.g. tearing or breaking of the foil by the tuftingneedles inthe case of products tufted through unsupported foil anddifiiculty in removing the water and/or other vehicle employed in dryinga latex or other like adhesive binder used to bond the foil to thetextile, the foil having a low vaporpermeability and, therefore, causingthe liquid vaporized during drying to pass through the body proper ofthe textile. The invention described in Ser. No. 765,267, obviates theaforementioned disadvantages and makes possible the highly effective useof aluminum foil for 3,728,204 Patented Apr. 17, 1973 dissipating staticcharge in carpeting or other textile products normally faced with astatic charge problem.

The principal object of the present invention is to provide a furtherprocess and product involving the use of aluminum foil in carpet or liketextile product for the purpose of dissipating static charge. Anotherobject of the invention is to provide a product having antistaticproperties and which is further characterized by the fact that, byvirtue of the use of foil as described herein, it is also flameretardant. Other objects and advantages of the invention will beapparent from the following detailed description of the invention andthe accompanying drawings wherein:

FIG. 1 is a flow sheet diagrammatically showing the present process; and

FIG. 2 is a fragmented perspective view, with parts in section forclarity, illustrating features of the present product.

Broadly stated, the product of the invention comprises a carpet having apile yarn surface, or other textile whose surface yarns are normallysusceptible to the generation and/or accumulation of static charges, andan electrically conducting metal foil, preferably aluminum, bonded tothe back of the carpet or like product through an appropriate adhesive,e.g. a latex formulation, the foil and adhesive being piercedlengthwiseand widthwise of the back so as to provide slits or holes inthe foil enabling vapor to escape through the foil and thereby obviatingthe necessity for the water or other vaporizing component of anyadhesive to escape from the back of the fabric through the body of thefabric and out the pile side thereof, the foil either being in directcontact with surface yarns adjacent the slits or holes or in sufficientproximity thereto to permit electrical discharge.

Generally speaking, the more direct contact between the foil and pileyarn, the better the degree of static control. The degree of staticcontrol also varies with the chemical and physical make-up of the pileyarn, the quantity of moisture present, the quantity and quality offoreign matter (usually dirt) present, the density of the yarn, the pileheight, the conductivity of the adhesive, the quantity of adhesive, thethickness of the adhesive and the quantity of void areas in the adhesivefilm. Piercing of the foil while the foil is in place on the carpetforces the foil closer to or into direct contact with the pile yarn,rearranges the location of the adhesive mass thereby causing more areaof voids and/or thin adhesive, and promotes mechanical adhesion to thefoil. In order to reduce static to the point where humans using thecarpet are unaware of the generation and/or accumulation of staticelectricity, approximately 2.2 kv., it is usually necessary to haveevery one inch length of pile yarn have at least one point where it iswithin .01 of the foil. It may be desirable to join the foil to anexternal ground although this may not be necessary.

The product of the invention may also include a foam or other secondarybacking material bonded to the foil, and at least a part of the desiredbonding between the foil and the secondary backing may be obtained byadhesive which extrudes or otherwise passes from between the carpetbacking and foil through the slits or holes to the back of the foil.

Referring more particular to the drawings, the numeral 1 in FIG. 1represents a supply roll of carpet 2 or a similar type of textileproduct which tends to generate and/or accumulate static charge. Forpurposes of illustration, the carpet may be a tufted product comprising,as shown in FIG. 2, a primary backing 3 with pile yarn 4 tufted back andforth through the backing to give the pile surface 5. It will beappreciated that pile surface 5 may be cut or looped as desired and thebacking 3 may be woven fabric or it may be a non-woven fabric comprisingnatural and/or synthetic fibers, usually jute or polypropylene, whilethe pile yarn may be spun or filament nylon, acrylic, polyester,polypropylene, rayon, wool and/or other fiber or fiber blend (such asnylon and stainless steel mixtures) normally employed for this purpose.A further example of a backing suitable for use herein is one preparedas described in my co-pending U.S. application S.N. 872,657, filed Oct.30, 1969.

According to the embodiment of the present process shown in FIG. 1, thecarpet 2 is taken from supply roll 1 and contacted on its back side witha roller coater 6 or the equivalent, latex adhesive formulated toprovide the desired adhesion being thus applied to the carpet from a pan7. The carpet then may pass over a knife 6' to control the quantity ofadhesive coated onto the fabric and/or to achieve the desiredpenetration into the fabric by the adhesive, and it thereafter goesaround a further pair of rolls 8 which serve to turn the carpet 2 overso that the side with the adhesive thereon faces upwardly and the pilesurface faces downwardly. Aluminum foil 9 is fed from supply roll 10onto the adhesive-coated surface of the carpet just before the resultingcomposite passes into the nip of a pair of rolls 11 and 12. Of theselatter rolls, roll 1 may be advantageously a smooth roll Wh-ile roll 12is preferably padded, the foil being forced firmly against the carpet bythe rolls 11 and 12 so that the foil tends to assume the contour of thecarpet. Typically, rolls 11 and 12 exert a pressure of 1-10 pounds perinch, for example, on the foil-carpet composite although obv iouslyother pressures may be used.

From rolls 11 and 12, the composite 13 is passed between rolls 14 and15. Preferably roll 14 is padded while roll 15 is provided with a seriesof equally spaced metal pins 16 extending along the full width andcircumference of the roll. Typically, pins 16 are on A3" to 1" centers.They serve to pierce the foil thus forming a plurality of approximatelyequi-spaced slits or holes extending across the foil and preferablyinwardly all the way to the carpet backing 3. These slits or holes,represented by the numeral 18 in FIG. 2, serve several purposes. For onething, the openings in the foil permit moisture vapor and the like topass through the foil. This greatly facilitates drying since it thus isnot necessary for moisture or other carrier in the adhesive to passthrough the body of the carpet during drying.

Furthermore, the piercing bf the foil permits some of the latex adhesiveto pass through the holes and serves, at least in part, as a bondingmedium for any secondary backing that might be applied to the foil sideof the carpet. Additionally, the pins, in piercing the adhesive andfoil, tend to push the pierced edges of the holes in the foil inwardlythrough the adhesive and into contact with, or in close proximity to,the yarns 4 making up the pile surface 5 so as to facilitate dischargeof static charge through the bases of these yarns and the foil. Also,the pins tend to form discontinuous areas in the adhesive 7 therebyenhancing electrical discharge to and through the foil. FIG. 2 shows inone instance contact between the \bottom portion of pile yarn 4 and aninwardly turned edge 20 of the foil 9 While other edges 20 are spacedfrom but in close proximity to the pile yarn. It will be appreciatedthat contact between the foil 9 and yarns 4 is not essential since theadhsive layer is usually so thin that the pierced foil and carpet yarnsare sufiiciently close to facilitate the discharge of statictherebetween.

Following passage between rolls 14 and 15 and the piercing of the foilas described above, the composite is dried and cured as generally shownby the numeral 22. Conventional drying and curing conditions may be usedand generally it is preferred to carry these operations out 1 4 variedand will be dependent on the nature of the carpet involved and otheroperating factors.

The adhesive composition used to bind the foil to the carpet backing orthe like may be any convenient adhesive which will bond effectively.Typically such composition comprises a latex or polyvinyl acetate,natural rubber, butadiene-styrene copolymer and/orbutadiene-acrylonitrile copolymer; or an ethylene-vinyl acetatecopolymer hot-melt solid adhesive. One such adhesive is availablecommercially as Elvax (E. I. du Pont) hot-melt formulation. Obviously, aconductive and/or flame retardant adhesive may be used advantageously.

Apart from the antistatic properties which are realized with the presentinvention, important further advantages of the product are its flameretardant and fire resistant characteristics because of the use of thefoil. These latter characteristics are obviously of considerableimportance from the standpoint of safety in use. The foil, because it isan excellent thermal conductor, serves as a heat sink and, because it isa nonporous substance, serves as a convection barrier and, because ofits physical properties, is a heat reflector.

It will be recognized that various modifications may be made in theinvention as described above. For example, if desired, a foam cushioningmaterial or other secondary backing 24 may be adhered to the foil sideafter the piercing operation as noted earlier, and part of the binder oradhesive for bonding the secondary backing to the foil may be spots 26of the adhesive 7 at the slits or holes in the foil. Alternatively thefoil may be coated with or laminated to a material on its back sidewhich is more easily adhered to a secondary backing material than plainfoil. An example of this is to adhere a foil/ paper laminate to thecarpet and then apply latex foam on top of the paper. Another example isto coat the foil with hot-melt adhesive so that it may be heat-sealed toa floor or secondary backing material. Still another modification is toapply foil which has been prelaminated to a secondary backing material,such as woven jute or Loktnft.

In another modification, a hot-meltable adhesive web, as employed inSer. No. 765,267, may be used with the latex adhesive composition. Insuch event, the system shown in FIG. 1 may be modified to includefeeding such adhesive web onto the back of the carpet either before orafter application of the latex adhesive but, in any event, before thefoil is applied to the backing.

In still another modification, on fabrics where additional flameretardance is desired at the expense of a lesser degree of control overstatic generation and/or accumulation, an adhesive with residual tackafter drying, curing and/or activating may be applied to a fabric in theconventional manner; then dried, cured and/or activated; and then thefoil may be laid or nipped onto the adhesive either alone orpre-laminated to a secondary backing material. The foil may or may notbe pierced. Leaving the foil unpierced provides a more flame resistantproduct because the convection barrier provided by the foil iscontinuous, the heat sink effect is maximized, and reflectance of heatby the foil is maximized; but provides less static control because theretends to be a greater distance between pile yarn and foil, and becausethe adhesive may have set before the foil is laid or nipped on, theadhesive may tend to be thicker on high points on the back of thefabric.

The characteristics of the aluminum or other metal foil are important tothe success of the invention. In particular, the foil should not only beelectrically and thermally conducting but it should also be sufficientlyductile to tend to conform to the bottom surface of the carpet fabricand yield therewith in use without fracturing. Thickness of the foil maybe widely varied as illustrated in the case of alunnnum, where typicalfoil thickness range is, for example, from .0002" up to .002" or evenhigher or lower. Actually it has been found that the thinnest availablealuminum foil possesses an adequate amount of conductive capacity todissipate static charge. Hence, in the case of aluminum foil, the keycriteria are the absence of processing oils or other contaminants, easeof handling, abiilty to withstand flexing, and conformability to thecontour of the carpet fabric and any cushioning material that might beused therewith.

Preferably the foil used in the present invention has the same width asthe carpet but this is not essential because less-than-full-width stripsof foil, either, overlapping at their edges or separated by strips notcovered by foil, extending lengthwise of the carpet, may be used.

External grounds may also be employed with the foil as indicated above.

For convenience of description, the invention has been described abovein connection with the processing of tufted carpet. However, it will beappreciated from the foregoing that the invention is also applicable toother types of carpet, e.g. woven carpet such as the Wilton andAxminister types, as well as other types of textile products whereantistatic and flame retardant properties, for instance, upholstery andwall covering fabrics, are important.

The scope of the invention is defined in the following claims.

I claim:

1. An antistatic and flame retardant textile product having a fabricbase with two opposed surfaces, one of said surfaces comprising yarnwhich is susceptible to the generation or accumulation of static chargeor having the quality of allowing flame spread, an adhesive on the othersurface of said base and an electrically and thermally conducting,static-dissipating metal foil of about .000 to .00 thickness bonded tosaid other surface of said base by means of said adhesive and pressuresuch that the foil and said other surface of said base tend to have acommon contour and the foil is positioned so as to be in directelectrically conductive contact with respect to said yarn.

2. A product according to claim 1 wherein said textile product is acarpet.

3. A product according to claim 1 wherein said foil is aluminum foil.

4. A product according to claim 1 wherein said foil is laminated to asecondary backing material.

5. A product according to claim 1 wherein said foil is joined to anothermaterial on its back side to render it better for later adhesion to afloor or secondary backing material.

6. A product according to claim 1 wherein the adhesive has residualtack.

7. A product according to claim 1 wherein a hot-melt web adhesive is oneof two or more adhesives used.

8. The process for making the product of claim 1 which comprisesapplying adhesive to the opposite surface of said textile product, thenapplying the foil against said adhesive and pressing the resultingcomposite together so that the foil tends to conform to the contour ofthe textile product of said surface and then drying and curing.

9. An antistatic and flame retardant textile product having a fabricbase with two opposed surfaces, one of said surfaces comprising yarnwhich is susceptible to the generation or accumulation of static chargeor having the quality of allowing flame spread, an adhesive on the othersurface of said base and an electrically and thermally conducting,static-dissipating metal foil of about .0002" to .002" thickness bondedto said other surface of said base by means of said adhesive andpressure such that the foil and said other surface of said base tend tohave a common contour and the foil is positioned in electricallyconductive relationship with respect to said yarn, said foil havingslits or holes therein.

10. A product according to claim 9 wherein the foil is pierced toprovide positioning thereof in close proximity to said pile yarns.

11. The process for making the product of claim 9 which comprisesapplying adhesive to the opposite surface of said textile product, thenapplying the foil against said adhesive and pressing the resultingcomposite together so that the foil tends to conform to the contour ofthe textile product, thereafter piercing the foil and adhesive layer toform a plurality of slits or holes therein lengthwise and widthwise ofsaid surface and then drying and curing.

References Cited UNITED STATES PJATENTS 3,293,105 12/1966 Koller 161-673,158,51-8 11/1964 Kessler 161213 3,510,386 5/1970 Goins et a1 161-673,325,323 6/1967 Forkner 15672 3,166,465 1/1965 Rahmes 161--66 3,537,94611/1970 Truax et al 161--66 3,582,444 6/1971 Ngo et a1. 161-65 WILLIAMA. POWELL, Primary Examiner J. J. BELL, Assistant Examiner US. Cl. X.RI

